Spare parts inventory management

ABSTRACT

A method for managing spare parts and tools for a manufacturing enterprise is disclosed. Historical demand values are statistically analyzed to determine optimal stocking levels for spare parts based upon required availability percentages, parts lead times, and the statistical distribution parts demand levels. Parts stocking decisions can also be based upon planned and preventative maintenance timeframes with such parts ordered on an as-needed basis in accordance with lead times. Spare parts inventory management can utilize an enterprise-wide computer system to integrate parts demand planning with systems used for engineering and other changes to manufacturing processes and facility maintenance systems. The computer system can perform varying degrees of the parts reordering and planning process and automate certain steps while providing for decision of other issues by parts management personnel.

BACKGROUND OF THE INVENTION

For as long as manufacturing processes have existed, there has been aneed for spare and replacement parts. Modern manufacturing processes maycomprise thousands of discrete parts and subassemblies, each of whichwill eventually require repair or replacement depending upon a myriad offactors such as the intensity of use and environmental considerations.Process maintenance is crucial to profitability for manufacturingenterprises, and entails scheduling for maintenance and repairs, andproviding that adequate parts and tools will be available to carry outsuch repairs in an expeditious fashion. Additionally, sufficient partsmust be available for unplanned parts replacements.

Modern manufacturing enterprises utilize many processes operating atfacilities scattered across the globe. Furthermore, the aggregate valueof spare parts purchased and held in inventory to support suchenterprises can reach into the hundreds of millions of dollars.Mismanagement of spare parts inventory carries two great risks: if sparepart stocks are inadequate, then the manufacturing processes cannotoperate at full profit potential; on the other hand, excess inventory ofunneeded spare parts represents a misapplication of capital that couldbe otherwise used in a more effective manner.

Despite the pressures for effective inventory management, somemanufacturing facilities which are part of a multi-facility enterprisestill manage spare parts independently of one another. This is due to anumber of factors, including the fact that oftentimes facilities willuse differing processes that identify the same parts under differingdesignations. Other enterprises may utilize a central repository ofspare parts that are distributed to facilities which keep their ownstock of certain parts, but part levels are managed based upon setstocking requirements, without consideration of actual parts demand,availability of parts outside the central store, the dynamic nature ofparts requirements, or capital investment implications. Accordingly,there is a need for an integrated parts management system to moreaccurately determine spare parts ordering and distribution needs formulti-facility enterprises that takes such factors into account.

One measure of the effectiveness of spare parts management is referredto as the “turns ratio,” which is found by taking the usage of spareparts inventory over a given time period and dividing by the inventorystock level for that period. A higher turns ratio results from anincrease in the amount of parts usage relative to parts kept in stock,and is indicative of more effective parts management than a lower turnsratio. For typical large-scale manufacturing enterprises, the turnsratio for spare parts inventory is around 1 or lower. Enterprises haveincreased turns ratios for sales inventory management, but have notachieved consummate increases in the turns ratio for management ofinternal inventories for spare parts and the like.

Manufacturing enterprises can use enterprise resource planning andaccounting systems such as SAP® to track manufacturing asset history andcosts. Additional computer systems may be used in the design andrevision of manufacturing processes. However, these existing systems arenot optimized for spare parts management.

SUMMARY OF THE INVENTION

A method for managing enterprise-wide component inventory can includethe steps of identifying a plurality of components, each of which iseither a spare part or tool used in support of a manufacturing process;maintaining at least one inventory store of the components, which caninclude both central hub and facility-based parts storage; calculatingan enterprise-wide demand plan for each of the components; and adjustingthe number of the component maintained in the inventory store based uponthe demand plan. The adjustment can include issuing or changing purchaseorders for spare parts, transferring spare parts between facilities, orselling excess spare parts.

Calculating the demand plan can take into account changes made inprocess parts requirements by engineering personnel, such as theaddition or deletion of parts or entire processes. When use of a part isdiscontinued, the demand plan can be calculated to run out existinginventory stocks to the fullest degree possible, and when a new part isadded, the plan can include consideration of lead times to ensure spareparts are available when the new part comes on-line. The method can alsoaccount for parts changes due to other factors such as originalequipment manager (OEM) changes.

The demand plan can be calculated based upon statistically-derivedsafety stock considerations based upon historical demand patterns sothat sufficient stores of parts are maintained to satisfy breakdowndemand for parts during lead time for reordering the parts in accordancewith a specified parts availability requirement. The demand plan canprovide for non-breakdown demand satisfaction through parts ordering inaccordance with planned or preventative maintenance determinations forparts replacements. The demand values can be identified using dataassociated with an enterprise resource planning computer system.

Historical usage of components can be tracked, including tracking dataregarding individual components such as repair history and location. Theparts can be tracked using barcodes, RFID chips, or other identificationindicia.

A method for managing enterprise-wide component inventory may includemonitoring at least one identification device associated with acomponent, the component comprising a spare part or tool used in supportof a manufacturing process, determining a physical location of thecomponent in response to the monitoring, and adjusting inventory datafor the component based upon the location of the component.

The step of monitoring can include scanning an RFID tag associated witha component that is in use in a manufacturing process or components instorage.

A method for managing enterprise-wide component inventory may alsoinclude identifying a plurality of components, each comprising a part ortool used in support of at least one manufacturing process, maintainingwarranty data for each component, evaluating component status basedcomponent data, including the history of the component and the warrantydata, providing for repair in accordance with the warranty data for eachcomponent if warranty coverage is available. The step of providing forrepair can include generating repair request and shipping documents forthe component to a repair service provider when warranty coverage isavailable.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figures, in which:

FIG. 1. illustrates a representative arrangement of manufacturingfacilities operated in accordance with the spare parts management systemand methodologies disclosed herein;

FIG. 2. represents an exemplary flow diagram for managing spare partsinventory in one embodiment of the management system; and

FIG. 3. represents an exemplary flow diagram of the steps for proactiveparts demand management in accordance with another aspect of a spareparts inventory management system as disclosed herein.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to present embodiments of a spareparts inventory management system, one or more examples of which areillustrated in the accompanying drawings, with like numeralsrepresenting substantially identical structural elements. Each exampleis provided by way of explanation, and not as a limitation. In fact, itwill be apparent to those skilled in the art that modifications andvariations can be made without departing from the scope or spirit of thedisclosure and claims. For instance, features illustrated or describedas part of one embodiment may be used on another embodiment to yield astill further embodiment. Thus, it is intended that the spare partsinventory management system disclosed herein includes modifications andvariations as come within the scope of the appended claims and theirequivalents.

Manufacturing Facility Topology

FIG. 1 illustrates an exemplary arrangement of facilities 10, 12, 14,and 16. Each facility may comprise one or multiple buildings in whichmanufacturing processes A, B, and C, or parts thereof, are carried out.The illustrated facilities are for example only; the methods of thepresent subject matter may be practiced with more or fewer facilitiesthan are illustrated in FIG. 1. Each facility may house a number of thesame, or different, manufacturing processes. In one embodiment, asillustrated in FIG. 1 at facility 10, the enterprise maintains one ormore parts warehouses where no manufacturing processes are actuallyoperated. The parts warehouses may be utilized as central stores toprovide parts to a number of facilities in a single- or multi-tier huband spoke arrangement. Alternatively, facilities with activemanufacturing processes can serve as hubs, with other manufacturingprocess facilities serving as spokes. The facilities may be physicallylocated any distance from one another, and are linked to anenterprise-wide computer network 19. Parts and materials transportnetwork 18 provides transportation and logistical support via truck,rail, air, and other transportation means.

Each facility has associated with it a spare parts inventory store orstores, shown by the dotted lines, which represent stocks of spare partsmaintained at the facilities. As illustrated in FIG. 1, two exemplaryspare parts types 20 and 20′ are shown for ease of explanation. AlthoughFIG. 1 depicts only two spare parts types, a spare parts inventorymanagement system as disclosed herein can be used with any number ofparts, including the multiple thousands of spare parts that are commonlyneeded in modern manufacturing processes. Additionally, as used herein,the term “spare parts” includes any other components used in support ofmanufacturing processes exclusive of the product or materials producedor operated upon by the manufacturing processes. Such components caninclude new and used spare parts, tools, tool kits, or processsubassemblies. The number of each spare part type that is kept ininventory may vary from zero on up.

A record of spare parts inventory on hand for each facility ismaintained using a computer database or other data compilation, accessedvia computer network 19. “Database” is used broadly herein so that theactual databases may comprise a combination of discrete databases,sub-databases, or alternatively a single, unified database, dependingupon the specific needs and efficiencies of a particular embodiment.

Foundation for Proactive Parts Inventory Planning

Cost savings and manufacturing process downtime reduction can both beachieved through proactive spare parts management based upon part demandforecasting, rather than reactive management based upon immediate needand fixed stock levels.

The first step is gaining an accurate picture of what parts arepresently kept in inventory and used in the enterprise's manufacturingprocesses. Typical manufacturing processes may require thousands ofparts to operate, and those parts requirements can change based uponchanges in the processes, such as upgrades or changes in workflow, aswell changes in the type or number of particular products aremanufactured using the processes. A large manufacturing enterprise willtypically have many processes in operation at any given time.Additionally, that same enterprise may be planning to bring stillfurther manufacturing processes into operation in the future.Accordingly, the enterprise will have a wide variety of parts requiredfor normal operation.

Despite differences, many of the manufacturing processes may in factutilize the same parts under different names. For example, severalotherwise-distinct manufacturing processes could all utilize a conveyorapparatus to move product through various stages of completion. Duringmanufacture, items such as diapers and tissue paper may both requirecutting and folding (or other manipulation) and may share certaincomponents such as blades or actuators. Otherwise-disparate processesmay have common maintenance needs, such as requiring a certain number ofspecialized electrical or plumbing toolkits to be on hand to allow forrepairs in case of a breakdown. A simplified instance of commonality ofparts is indicated in FIG. 1. Process A utilizes part 20 and process Butilizes part 20′. Process C is different from A and B, but utilizesboth 20 and 20′.

All of these distinct parts utilized in support of differingmanufacturing processes may have initially been specified under distinctpart numbers, however. Such a specification leads to an inflated levelof indicated parts demand since each process will need its own stable ofparts. The inflation can be revealed by assigning common partidentifiers to common part types. The system as disclosed hereinidentifies the parts independently of the process in which they areused, and uses common identifiers for common part types. The partidentifiers can be part numbers or other alphanumeric designations. Theparts can be identified by utilizing a generated designation assigned toeach part, and this can include cross-linking disparate numbers, such asmachine part numbers, enterprise-assigned numbers, and manufacturer partnumbers, in a computer database. The physical parts themselves can beidentified by alphanumeric tags, bar codes, or an RFID chip or chipsassociated with the part or containers in which the part is stored.

Once components, such as the parts 20 and 20′ illustrated in FIG. 1 areidentified by common designators for like components, the inventorylevel of each component is determined. This can be achieved by scanninga barcode or RFID tag associated with each part that is stored in theinventory stores of the facilities. Parts can be similarly scanned asthey enter or leave the facilities, or are moved from inventory storesto actual use in processes. Other data entry means may be utilized aswell. The identification of parts and determination of current inventorylevel and distribution is represented generally at step 100 of FIG. 2.

For instance, in FIG. 1, facility 16 has implemented a barcode-basedsystem. The inventory database is updated as parts are scanned in or outof the parts store by worker 22 at facility 16 to show the partsstocking level. Facility 12 has implemented an RFID-based system, andworker 24 need only move within range of his handheld RFID scanner toregister a part in the database. Facility 14 uses a large-scale RFIDscanner 26 to automatically scan the entirety of parts moving in or outof its inventory store (via truck 27 in FIG. 1).

Part information can therefore be maintained to as high a level ofdetail as desired, both for part types and particular instances ofparts. In one embodiment, for each part, the database can includeinformation on acquisition date, manufacturer, country of origin, modelnumber, manufacturer part number, manufacturer serial number, partlocation data, plant section and room, status, manufacturing assetnumber and sub-number, operation lead time offsets, cataloguinginformation, desired stocking levels and location such as at-plant or ina central store, normal issue quantity, expected plant annual usage,plant current safety stock, central stores current safety stock, andplant delivery time.

Parts Demand Forecasting

Presently, manufacturing facilities can use specialized software such asSAP® which includes plant maintenance modules allowing for planning ofmaintenance cycles based upon part performance data, such as mean timebetween failure, maintenance interval calculations, and the like. Thissoftware can also be used to track parts maintenance requests, and suchdata can be used to separate the breakdown demand level for parts fromthe non-breakdown demand level. The non-breakdown demand levelrepresents the need for parts that are planned to be taken out ofservice, such as in accordance with planned maintenance cycles. Thebreakdown demand level reflects parts that must be kept on hand (safetystock) in order to keep a manufacturing process operational upon theotherwise-unplanned failure of a part.

Once a group of facilities have begun actively managing their individualspare parts demand levels, the data for each of the individualfacilities can be cross-referenced and combined to develop a cross-plantunified demand plan for the entire enterprise. As shown in FIG. 1,calculations based upon the usage of processes A and C will result incertain demand levels for component 20, while B and C will have demandlevels for component 20′. Using specialized software tools, thisinformation can be extracted from data maintained for each facility andcombined to determine the total level of breakdown demand andnon-breakdown demand for each of parts 20 and 20′ across the entirespectrum of facilities.

This enterprise-wide demand calculation can be used to adjust the numberof spare parts kept in inventory at parts hubs and individualfacilities, based upon such factors as maintenance needs, production andpart lead times, changes to existing processes, addition of newprocesses, changes to parts by original equipment manufacturers (OEMs),and a determination of optimal spare parts capital investment. Thedemand calculation is represented generally at 110 in FIG. 2. and isshown at 115 as taking into account various considerations such as thoselisted at 115 for exemplary purposes. The demand calculation can proceedas discussed in further detail below, and may also consider otherfactors deemed relevant to spare parts demand planning by one skilled inthe art.

Non-Breakdown Demand

The system can provide for non-breakdown demand for parts by taking intoaccount parts lead times and ensuring that adequate parts are on-handwhen the parts replacement is planned. Using this data, facilities canbe transitioned to purchasing parts for planned and predictedmaintenance based upon a combination of planned maintenance cycles, partperformance data, and parts lead times; in one embodiment, such partscan be eliminated from the central stores in favor of ordering parts fordelivery in accordance with planned needs. The predicted maintenancedetermination can be based upon values such as mean time between failure(MTBF), both as provided by the part supplier and as derived from actualexperience using the part, and other concerns such as the environment inwhich the part is used.

Statistical Analysis of Breakdown Demand

For non-breakdown demand, statistical analysis can be performed todetermine the best level of safety stock inventory to maintain incentral stores. For example, analysis of breakdown demand may indicatethat a manufacturer has enough parts on hand across facilities to keepthe facilities operational in the event of a part failure. Rather thantying up capital in purchasing more of those same parts based upon afixed purchasing target, the money can be invested in a non-depreciatingasset until truly needed to purchase more breakdown parts, orre-allocated to stock parts that are needed for safety stocks, or topurchase parts to satisfy non-breakdown demand. The statistical analysiscan utilize historical parts demand levels maintained in theenterprise's computer database(s).

The parts management system can be configured to evaluate parts demandand provide for reordering parts once the stock level has reached atheoretical reordering point. By providing for parts reorder at such apoint, the system ensures that sufficient spare parts inventory ison-hand to meet projected breakdown demand. For a given part, thetheoretical reordering point is defined as the expected demand duringlead time for the part plus the theoretical safety stock. The expecteddemand during lead time can be determined by the average usage of thepart multiplied by the lead time for the part. The theoretical safetystock represents the amount of inventory that must be kept on hand tomeet above-average demand for the part. In one embodiment, the “leadtimes” used in calculating projected parts demand are actually partdelivery time values based upon lead times provided by OEMs and astatistical analysis of actual delivery times in practice.

The theoretical safety stock is calculated using statistical theory, andis a function of the lead time for the part, the daily variance indemand for the part and the required availability for the part,typically represented as a required availability percentage (forexample, the part must be available 95% of the time). Higheravailability requirements require a higher level of safety stock to bemaintained. The average demand, daily variance, and standard deviationof demand rate can all be calculated from historical demand datamaintained in the parts and manufacturing database(s).

The spare parts inventory management system can also consider economicfactors in determining spare parts ordering quantities. For instance,the cost of maintaining a parts inventory is more than simply the costof the buying the parts. Rather, the total cost includes the actual costof the parts, the cost of ordering the parts, and the cost of holdingthe parts. From these values, an economic order quantity can becalculated based upon such factors as the annual price of parts, annualordering costs, and annual holding costs. The demand for parts can becorrelated with the economies of obtaining the parts to determine anoptimal ordering amount that is based upon both the needs of themanufacturing processes and the financial realities of the enterprise.Certain parts stocking decisions may require the intervention of ananalyst or other personnel. In one embodiment, the spare parts inventorymanagement system is configured to automate some parts stockingdecisions and leave others for decision by plant personnel based uponparts pricing considerations and amount of use.

Proactive Spare Parts Inventory Management

In addition to integration with manufacturing management computersystems such as SAP®, the spare parts management system can beintegrated with an existing engineering design system or systems toenable proactive parts management. When engineering changes are made,such as adding a new process or redesigning an existing process, theparts requirements due to the changes can be taken into account in thespare parts management system demand plan calculations, as generallyillustrated in FIG. 3.

For example, assume that the engineering staff at facility 16 implementsa change to process C so that it utilizes two units of part 20′ ratherthan one as shown in FIG. 1. The engineering design change triggers anotification (indicated at 200 of FIG. 3) to the parts managementsystem, which then assesses the changes in the engineering partsdatabase. In an alternative embodiment, the spare parts managementsystem periodically queries the engineering system to check for changesin parts lists and requirements. In any event, the increase in thenumber of part 20′ is ultimately factored in to adjust the calculateddemand for spares of part 20′, both for breakdown and non-breakdowndemand purposes.

An engineering change to an existing process may delete the use of apart from an existing process as illustrated at 215 of FIG. 3. Deletionmay be due to a change in the product manufactured using the process,changes to parts by respective OEMs, or other concerns. For instance,assume that due to a product redesign, both processes B and C arealtered in a manner that eliminates the use of part 20′. This changewill be implemented in the engineering project database. The change tothe processes will trigger a notification to the parts managementsystem, which will evaluate the bills of material and ascertain thatpart 20′ will no longer be required in the future. As indicated at 215,225, and 235 of FIG. 3, the system considers the effective date of thechange, the planned demand for part 20′ calculated up to that point, andexisting inventory stocks, to adjust the enterprise-wide demand plan torun-out the existing inventory of part 20′ so that no, or minimal,excess of the part remains in the spare parts inventory. Depending uponwhen the part will go out of service, the adjustment to the demand planmay include reducing or canceling orders of spare part 20′; forinstance, a change planned far in advance for a part not kept in stockat high levels will result in a more minor change to the demand planthan a change to be implemented sooner for a part that is highlystocked.

Engineering changes can also comprise the addition of entirely newprocesses as illustrated generally by 216, 220, and 230 of FIG. 3. Theparts maintenance planning system can accordingly determine initialstocking requirements and take action to procure needed components. Asin the case of parts addition or deletion, the parts maintenanceplanning system evaluates the bill of material obtained from theengineering data for the new process. Based upon existing partsinventory, the new parts required, the effective date that the newprocess will come on-line, and the forecast demand for parts new andold, the demand plan can be modified so that adequate stocks areavailable to bring the new process on line.

Adjusting Spare Parts in Inventory

Once a demand forecast has been obtained, at step 120 as illustrated inFIG. 2, part ordering criteria such as required parts availability, leadtimes, and economic considerations as discussed above are consideredaccording to rules specified by parts management personnel. At step 130,the parts management method proceeds to check the planned part order forcriteria which may indicate the particular part may require furtheranalysis. If so, the part is flagged for follow-up as illustrated at 135for intervention by a skilled person before ordering is to proceed. Oneskilled in the art will note that intervention by parts managementpersonnel may occur at any stage in the parts management processdepending upon the particular needs of the manufacturing enterprise andthe criteria specified for the parts management system. Assuming noexceptions, the final step as illustrated at 140 is for parts orders orother instructions to be generated. For instance, parts can be orderedfrom OEMs or transferred between facilities.

Logistical Considerations

For all parts stocking decisions, lead times for the parts can also beconsidered, both in considering forecast demand as well as ensuring thatthe parts are delivered as soon as they are needed. For example,consider the case of a new process coming on-line ninety days from thedate changes are implemented in the engineering system. Further assumeit requires two components—one with a seven-day lead time, and a secondwith a thirty-day lead time. After calculating demand for the parts, theinventory management system can generate the required purchaseauthorization forms and place orders for the parts—ordering the first(seven-day lead time) part for delivery eighty-three days after thetriggering change and ordering the second (thirty-day lead time part)for delivery sixty days after the change.

Plant demand forecasts also incorporate a determination of the optimalgeographical distribution of spare parts that are on-hand, as well asordering and delivery strategies. Certain parts may be stored in acentral hub or hubs, while others are earmarked for distribution tofacilities for storage. For instance, parts that are produced nearfacility 14 and not subject to high system-wide demand can be deliveredfor storage at facility 14, and then allocated for transfer of someunits to the central store 10 and/or other facilities rather than directshipment from the parts manufacturer to facility 10. This can save onshipping time and cost. Parts that are found to be in demand system-widemay be stored at a hub for later deployment to facilities. The partsmanagement system can take into account such factors as manufacturerlead times for parts delivery and facility lead times for parts demandin determining optimal parts positioning.

Any parts tracking currently using bar codes may instead use smart tagsor UWB identification devices. As will be apparent to one skilled in theart, “Smart tags,” “UWB identification devices,” and “RFID tags” are allused interchangeably herein to refer to remotely-accessible data storagedevices physically associated with a component. For example, instead ofusing a bar code to identify a part or parts kit shipped to a productionfacility in a parts management system, a smart tag embedded in the partor its packaging could be automatically read when it is received at theproduction or storage facility. The electronic code generated couldeither uniquely identify the part, allowing links to online partattributes, or the smart tag could be programmed to contain the neededinformation, such as part installation and repair history, warranty andrepair instructions, and the like.

Use of RFID tag technology can provide for real-time indications of partinventory and location. In this manner, although parts are physicallylocated in differing locations, the use of database tracking incombination with the distribution network essentially provides for anenterprise-wide central storage facility. As indicated at 26, partsshipments could be scanned as they arrive at the facility on a deliveryvehicle and logged into the parts database without need for facilitypersonnel to sort and identify the parts. Alternatively, RFID scanningby inventory personnel such as indicated by worker 24 at facility 12could be employed.

The RFID tag, or other identifying information, can be tied toindividual instances of parts to track part usage, maintenance, warrantyinformation, or other part-specific data. Usage data for individualparts and aggregates of the same type of part can be used to determinereal-world failure data such as mean time between failures. Thecalculated value can be compared to information provided by themanufacturer and can be used to fine-tune demand forecasts forparticular facilities and the manufacturing concern as a whole.

In addition, process bills of materials may be automatically checked byverifying that proper parts have been installed, based on RFID scannersreading smart tags of the parts or parts assemblies placed in theprocess machinery. Parts inventory management may also be simplified byusing UWB transmitters or smart tags to track the physical location ofparts within the central store, manufacturing location, or otherfacility. With UWB devices, triangulation of an emitted signal maypermit location of its source, much as in GPS systems. With RFIDtechnology, scanners and detectors may read and record the location ofnumerous parts in a storage facility, either by passing a scannerthrough the facility or by having multiple scanners in the facility thatdetect objects within a short distance of the scanner. The part'slocation can be noted in the data maintained for the part. Based uponthe part's location, the inventory level can be adjusted on an ongoingbasis, whether the part is utilized in a process, in storage, intransit, or for other purposes.

In addition, smart chips or UWB devices worn or carried by the inventoryand maintenance personnel may be used in lieu of a paper checklist torecord the completion of general housekeeping duties, machine healthchecks, inventory checks, or other actions required by GoodManufacturing Practices.

In another embodiment, smart chips or UWB devices worn or carried byoperators may be used to track and record actions of specific operators.For example, a smart tag identifying an operator may be read by thevarious input and control devices associated with an EWMA system orother HMI (human-machine interface) systems (e.g., a distributed controlsystem) to verify the identity of the operator. If the operator enters arestricted area or physically modifies a portion a machine or moves apiece of spare parts inventory, RFID readers in certain locations ofinterest may track the physical presence or movement of the operator inproximity to the part and may associate that operator with changes madeto the machine or inventory during that time and in that location, forpossible subsequent troubleshooting or problem solving analysis.

By way of example, RFID tag and RFID readers, under the name Intellitag500, may be purchased from Intermec Technologies Corporation of Everett,Wash., and Intermec's Amtech Systems Division in Albuquerque, N. Mex.,or the RFID reader may be a Commander 320 13.56 MHz RFID reader,manufactured by Texas Instruments of Dallas, Tex. Other automaticidentification and object tracking systems may be used such as RF SAW(radio frequency surface acoustic wave) technology from RF SAW, Inc.(Dallas, Tex.).

Additional Considerations in Parts Inventory Planning

A warranty management module can be integrated into the spare partsinventory management system to further streamline the repair process andoptimize asset utilization. The warranty module can track warrantycoverage and claims made based upon the histories of individual parts.For example, a database can contain the length or other measure ofwarranty coverage, what types of repairs are covered, where to ship apart for repair, and other information needed to effectuate the repairprocess. Certain part repairs may not be covered based upon the cause ortype of failure, and the warranty module can evaluate suchconsiderations based on stored data for the part or prompt users formore information.

When a part is removed for maintenance or due to part failure,information maintained within the database can be accessed to determinewhat warranty coverage, if any, is available for the part. For example,warranty coverage could depend upon the length of time from purchase forcertain parts, or may depend upon the length or amount of use forothers. A part may be covered for only a certain number of hours, andthe warranty module can evaluate whether coverage is available based onthe history of the part. If warranty coverage is available, the partsmanagement system can then generate the requisite shipping and warrantyclaim documents and instructions. The part can then be shipped to theOEM or other repair service provider in accordance with warrantyprocedures.

In one embodiment, the spare parts inventory management system isextended by additional software enabling integration and interfacingwith parts suppliers. Rather than issuing spare parts purchase ordersalone, the spare parts management system provides the demand plan orportions thereof to parts OEMs. OEMs can then provide for adequatemanufacturing capacity or pricing breaks based upon the demand forecast.

General Considerations

It will be apparent to one skilled in the art of parts inventorymanagement that the methods and systems disclosed herein can beimplemented utilizing computer software. Such software includesobject-oriented and other programming languages, as well ascross-application programming frameworks such as the .NET® framework ofthe Microsoft Corporation. One or more structured or unstructureddatabases can be accessed to store, retrieve, and change informationaccording to rules and calculations in accordance with the methodologiesdisclosed herein. The parts inventory management system disclosed hereincan be implemented on a single computer or across several computersystems, and may make use of or change data stored in and by otherunrelated computer systems depending upon the optimal configuration fora particular enterprise. The parts inventory management system may beimplemented in and practiced using a combination of discrete sub-modulesor as a unified piece of software. Furthermore, the data utilized inoperating the spare parts management system can be transmitted viaprivate network, the public internet, or a combination of networks.

Various data input and output schemes and devices can be used incombinations that best suit the manufacturing facilities supported bythe system described herein. For instance, a web-based front-end to thedatabase is used in one embodiment to allow users to access and modifyparts and availability data and requirements. The database can beaccessed via any computing device appropriately linked to a network withaccess to the parts inventory management system. These devices caninclude personal computers, terminals and servers, and portablecomputing devices such as PDAs. Parts information can be enteredmanually, via RFID scans of a tag or tags associated with parts, viabarcode scans, or by any other conversion of parts identification datainto machine-readable format to associate a particular part with datastored in the computer system.

Decisions on stocking requirements, purchase authorizations, and leadtimes can be based upon rules entered into the computer system, and becompletely or partially automated and present options or authorizationsvia a computer interface for management approval/alteration. In oneembodiment, parts are divided into categories based upon usage, cost,and potential savings and the degree of management by the systemdisclosed herein is varied accordingly. For instance, reorderingextremely low-cost or standardized items such as bolts or washers may bemanaged by individual facilities since the savings potential from usingdemand management as disclosed herein is minimal. For other parts,management intervention may be prompted by the forecast demand meetingcertain predefined criteria such as illustrated at 130 and 135 of FIG. 2and discussed above. For example, if a part demand forecast isexceedingly high, exceedingly low, or does not fit expected models, thepurchase or stocking decision can be brought to the attention of partsanalysts or managers.

1. A method for managing enterprise-wide component inventory, comprisingthe steps of: a. identifying a plurality of components, each comprisinga part or tool used in support of at least one manufacturing process; b.maintaining at least one inventory store of the components; c.calculating an enterprise-wide demand plan for each of the components;and d. adjusting the number of the component maintained in the inventorystore based upon the demand plan.
 2. The method of claim 1 wherein thestep of calculating a demand plan includes responding to a triggerinitiated by changes in a component bill of material for a manufacturingprocess.
 3. The method of claim 2 where the trigger is initiated by thedeletion of a component from a process, and the demand plan iscalculated to run out the remaining inventory of the component.
 4. Themethod of claim 2 where the trigger is initiated by the addition of apreviously-unused component, and the demand plan is calculated toprovide for an initial stocking level of the component so that thespares are available to meet demand as of the effective date of serviceof the previously-used component.
 5. The method of claim 1 wherein thestep of maintaining at least one inventory store includes storing aplurality of components at a central location, and wherein calculating ademand plan includes determining a safety stock level for the componentsbased upon statistical analysis of prior demand, including lead timesfor the components.
 6. The method of claim 1 further comprising the stepof tracking the history of the component, and wherein the history isutilized when calculating the demand plan.
 7. The method of claim 6wherein the history that is utilized in calculating the demand planincludes the frequency of failure of the component.
 8. The method ofclaim 6 wherein the step of tracking the history includes maintaining arecord of at least one individual instance of the component.
 9. Themethod of claim 8 wherein the record maintained includes a history ofrepairs to the individual instance of the component.
 10. The method ofclaim 8 wherein the record maintained includes the physical location ofthe individual instance of the component.
 11. The method of claim 8wherein the step of tracking includes scanning at least one RFID deviceassociated with the individual instance of the component.
 12. The methodof claim 5 wherein the resulting turns ratio is greater than
 1. 13. Themethod of claim 12 wherein the resulting turns ratio is greater than2.5.
 14. A method for managing enterprise-wide component inventory,comprising the steps of: a. identifying demand values for spare partsused in support of a plurality of manufacturing processes located atmultiple facilities; b. maintaining at least one inventory store of thespare parts; c. separating breakdown demand for each spare part fromnon-breakdown demand for each spare part; d. determining an averagedemand level for each spare part; e. calculating a theoretical safetystock level for each spare part based upon an analysis of thestatistical distribution of breakdown demand values for the part, theplanned delivery time for the part, and an availability requirement forthe part; f. calculating a forecast demand for each spare part basedupon the average demand level, planned delivery times, and theoreticalsafety stock level; g. placing orders for each spare part such that theinventory store contains sufficient numbers of each spare part to meetthe calculated demand; and h. placing orders for each spare part suchthat sufficient parts are delivered to facilities in accordance withplanned delivery times to meet non-breakdown demand.
 15. The method ofclaim 14 wherein the inventory store is a central hub serving multiplemanufacturing facilities, and the parts orders are placed such that thecentral hub contains sufficient numbers of each spare part to meetcalculated demand for all the facilities associated with the hub. 16.The method of claim 14 wherein the demand values for spare parts areadjusted in response to a change in process parts requirementsdiscontinuing use of a part, and wherein the forecast demand adjusted torun out inventory of the discontinued part.
 17. The method of claim 14wherein the demand values for spare parts are adjusted in response to achange in process parts requirements adding a new part, and wherein theforecast demand adjusted to provide for an initial stocking level of thenew part.
 18. The method of claim 14, wherein the demand values areidentified using data associated with an enterprise resource planningcomputer system.
 19. A method for managing enterprise-wide componentinventory, comprising the steps of: a. monitoring at least oneidentification device associated with a component, the componentcomprising a spare part or tool used in support of a manufacturingprocess; b. determining a physical location of the component in responseto the monitoring; and c. adjusting inventory data for the componentbased upon the location of the component.
 20. The method of claim 19,wherein the step of monitoring includes scanning an RFID tag associatedwith a component that is in use in a manufacturing process.
 21. Themethod of claim 19, wherein the step of monitoring includes scanningRFID tags associated with a plurality of stored components.
 22. A methodfor managing enterprise-wide component inventory, comprising the stepsof: a. identifying a plurality of components, each comprising a part ortool used in support of at least one manufacturing process; b.maintaining warranty data for each component; c. evaluating componentstatus based component data, including the history of the component andthe warranty data; and d. providing for repair in accordance with thewarranty data for each component.
 23. The method of claim 22 wherein thestep of identifying includes monitoring at least one identificationdevice associated with the component.
 24. The method of claim 23 whereinthe identification device comprises a smart tag emitting a radiofrequency signal, and the step of identifying comprises receiving, froma scanning device, the emitted radio frequency signal.
 25. The method ofclaim 22 wherein the step of providing for repair includes generatingrepair request and shipping documents for the component to a repairservice provider when warranty coverage is available.